1. Field of the Invention
The present invention relates rotating cutting tools, and more particularly, to rotating cutting tools having at least one interchangeable guide insert. The present invention also relates to interchangeable guide inserts.
2. Background Information
Such rotating cutting tools are normally drilling tools having a shank which forms the support part or a shank together with drilling head which together form the support part for the interchangeable cutting insert. Rotating cutting tools can penetrate deep into the workpiece, wherein it has to be ensured on account of the freely projecting length of the cutting tool that said cutting tool remains sufficiently stable and neither bends nor wobbles.
It is known from US 2010/0104385 A1 to laterally provide on the support part, here the shank, a plurality of “guide inserts” distributed over the circumference. These guide inserts are there for guiding the cutting tool laterally in the drill hole. Normally, the cutting inserts are arranged symmetrically on the cutting tool in such a way that, under normal cutting conditions, the cutting forces act substantially symmetrically and thus no lateral resultant force is produced which would cause the cutting tool to bend. However, the cutting tool can also encounter an already existing opening during the drilling, such that a lateral force acts on the end of the cutting tool, and this lateral force could lead to bending of the shank. The guide inserts, which rotate very close to the wall of the drilled opening, then come into contact with the drill hole wall and stabilize the cutting tool. Owing to the fact that the guide inserts are separate parts which are detachably fastened to the shank or support body in a nondestructive manner, they can be exchanged in the event of wear, but in particular can also be set with regard to their position and orientation.
Previous guide inserts were fastened to the support part via screws, which constitute retaining means. To this end, the guide insert has a central through-hole and, in the region of the through-hole, a recess which runs in the circumferential direction and in which the screw head lies.
However, it has been found that, despite the deeper-set screw head, drilling chips get caught in the region of the screw head, and so said drilling chips easily scrape along the inner wall of the drill hole and damage its surface. In addition, after prolonged use, a layer of compressed drilling chips forms around the screw, and these drilling chips make it difficult to drive the screw if it is to be released.
Accordingly, there exists a need for improved rotating cutting tools which utilize one- or multi-piece support parts.